Wave signaling system



Oct. 2, 1928.

H. W. HOUCK WAVE SIGNALING SYSTEM Filed March 5, 1925 2'Sheets -Shee N INVENTOR BY I Hum! xm w 41 w @Mib, W," 5 9 14 TITORNEIYJ Oct. 2, 1928.

H. w. HOUCK WAVE SIGNALING SYSTEM- Filed March 1925 2 Sheets-Sheet 2 IN VEN TOR QM f TTORINEYLY Q 1 UNITED s'rA'r-Es uan! W. 30110:, or we omen, raw mas'mr, mission, at ABSIGN- PAra roFFlc-E.

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Application filed mirth a, 1928. Serial m5. 022,591.

Thisinvention relates to improvements in .the super heterodyne system of receiving and indirectly amplifying radio frequency electrical oscillatory energy described in U. S. 6 Letters Patent to E. H. Armstrong No.

1,342,885 and it is the object of this inven- 131011 to provide a highly eflicient and stable self heterodyne frequency converting method and apparatus in a super heterodyne stem 10 whichwill'enable more reliable reception of signals, particularly radio phone broadcast si als, with .a minimum of interference while at the .same time enabling a very high degree of selectivity to be secured as between 16 stations operating on-but very slightly different wave lengths. Another result achieved by the invention is that reradiation of the local 1y generated oscillations produced bythe self heterodyne is eliminated to the point where '80- it is a negligiblefactor. 4

As is well known the su er heterodyne stem of reception and in lrect amplifica- Y tlon com rises converting short wave si a1 energy w ich cannot efliciently be amplified 28 andreceived directly, (at least with the pres ent type of vacuum or electron tubes) down to some readily amplifiable intermediate radio frequency which may then be' readily amplified, detected and indicated. This fre- 30 I quency conversion is generally accomplished by the heterodyne principle and in U. S. Letducing the local oscillations which are combined with the incoming energy and the other -a rectifier which converts or rectifies the combined locally generated and incoming oscillations to produce a third frequency, gener- 48 ally equal to the difierences between the local and incoming freque'ncies' altho a frequency equal'to the sum thereof may be obtained. I

'. The normal self heterodyne has the disad vantage that in order'to generate the local or heterody'ning frequency which in the case of thef'su'per heterodyne system should difler from the incomin signal frequency by a third readily amphfiablera-dio frequency, it must be so far mistuned from the signaling intermediate radio frequency.

frequency that the greater vpartof otherwise available resonant amplificationis lost.

In accordance with the present invention 9 the, difliculty arising out 'of-mistuning a self heterodyne system is eliminated for allpractical purposes by providing'two circuits in the self heterodyne arrangement associated with an electron discharge device or so called vacuum tube-having a cathode, an anode and Y control electrode. One of the circuits so provided may be tuned o the frequency of the incoming signal energy andthe other or aux-. lliary circuit may be tuned to a fundamental frequency which differs by a large amount from the signaling frequency and by a feedback or regenerative circuit arrangement causes the tube or electron device to produce oscillations ofthe desired fundamental frequency together with harmonics thereof. Thefu'ndarnental frequency is'a sub-multiple of the desired heterodyning frequency prefer:

"ably so chosen that the frequency of its second harmonic differs from the incoming signal energy by a readily. amplifiable third or mtermediate radio frequency. Of course, other sub-multiples with other sufliciently strong harmonics maylbe used'andin this .event the difference infrequency should also be the readily amplifiable intermediate radio frequency. The harmonic oscillation so'gen f erated is then combined'with the incoming signal energy oscillation and the combination is then rectified or converted by the self-heterv odyne tube to produce the readily amplifiable The result is an absolutelystable'self heterodyne in which an adjustment of either tuned circuit can be made without afie'cting the other and in which the frequency conversion takes place with equal or better efficiency than with a two tube separate heterodyne arrangement. Further, for all practical purposes the art that while it is possible to have two tuned circuits in; a self heterodyne system, one tuned to the incoming signaling fering from the incoming energy by the de. sired. intermediate frequency the arrangement would result ina highly critical organarrangement may be considered non-radiatmg. h It will'be understood'by those skilled in the e u y I and the other to afundamental frequency dif- 7 y ization' and in addition" would reradiate'i- I Moreover, such a critical system could not be controlled with success in practice since any change in the tuning of one circuit would 'produce great reaction on the other circuit and thereby tend to throw the whole system out of adjustment. I

Referring now to the drawings and the ance with the invention whereby unmodu- 'lated continuous wave signals may be indirectly amplified and received.

Referring now to Figure 1; the collector of theincoming signal energy-the antenna system 1-2, which as is well understood may be of any ofthe well known forms including a loop, is associated by means of the primary 3 with the secondary 4 of the high frequency transformer 5 and the grid-filament circuit 6.7. The self heterodyne system includes a vacuum or electron tube 8 having a cathode 9, an anode 10, and, ontrol electrode 11. Associated with these e ements are the tuned circuits 4-12 and 13-14 connected in the grid cathode or filament circuit 6, 7. The circuit 4-12 is tuned to the frequency of the incoming energy while the circuit 13-14 is preferably tuned to a fundamental frequency equal to one half the frequency of the incoming energy, plus or minus, one half of the de sired intermediate or third readily amplifiable fre uency. In this way the second harmonic lwhich is twice thefrequency of the fundamental) differs in frequency from the incoming energy by the desired intermediate frequency. It has already been pointed out that other harmonics, if of sufiicient amplitude may be employed provided they differ in frequency from the incoming energy'by the intermediate frequency which it is desired to produce. 1

The tuned circuit 13-14, by means of the feed-back circuit 15-16-17 causes the tube I 8 with its associated circuits to produce oscillations of the desired fundamental frequency circuit 4-12, (the frequency of the incoming oscillations) no reaction is produced'in circuit 4-12, by the circuit 13-14, or vice'versa,

if the electrical constants of each are varied in the course of operation. Moreover, with the present arrangement the resonant amplification is retained'wi-th a corresponding gain in efficiency.

. The incoming energy oscillation and the locally produced harmonic oscillation'generated by the 'tube 8 anditsassociated circuits areeombined in the said circuits and are rectified or conv erted by the tube 8, to produ'ce'the desired third readily amplifiable intermediate frequency oscillations in the circuit 18-19, in the plate-filament circuit 16-17, of the tube 8 which circuit (18-19) is tuned to the frequency of said intermediate oscillations.

The resulting intermediate radio frequency oscillations are then impressed on the input circuit 20-21, of a high fi'equency amplifier 22 which may be so designed as to'amplify 'most efiiciently the particular intermediate frequency which it maybe desirable to. produce by the self heter'odyne arrangement above described. The resulting amplified intermediate frequency oscillations may then be detected and indicated respectively by the tube 23, and the telephones 24, or applied to some other form of indicating device.

In Figure 2 which in all fundamental respects shows a system similar to that of Fig: ure 1, provision is made for the reception of unmodulated continuous waves, that is, the reception of straight continuous wave telegraphy. The operation of the system will be understood from the following explanation:

As in the case of Figure 1 the incoming energy will be collected' by the antenna system 30-31, converted by the self heterodvne system 32 and the resulting intermediate frequency oscillations thereby produced amplified by the amplifier 33. lhe resulting amplified intermediate radio frequency oscillations are then impressed on the input. circuit 34-35, of a second self heterodyne system 36, the auxiliary circuits 37-38, thereof being tuned to a fundamental frequency equal to one half the frequency of the-intermediate frequency, plus or minus the desired audible .beat frequency to be produced in the output circuits 39-40, of the system 36. This, of course, assumes that the secondharmonic of the second locally generated oscillation is utilized to interfere with intermediate frequency oscillations and it will beunderstood in this case that the second harmonic should differ in frequency from the intermediate frerange of audibility and preferably by about one thousand cycles. The rectifying action of the self heterodyne 36 will, therefore, produce in the indicating telephones 41a beat note of audible frequency.

It will be understood, of course, that the process of frequency transformation and amplification can be repeated with the systems Patent No. 1,342,885.

I claim:

1. Apparatus for receiving and amplifying a high frequency oscillatory energy and producing energy corresponding thereto and of lower frequency, comprising an electron discharge device having acathode,-an anode and a control electrode, a tuned circuit associated with said control electrode and detershown in Figures 1 and 2 as many times as desired, as explained in United States Letters mining the fundamental frequency of said electron discharge device as an oscillator, a

second circuit also associated with said con-.

trol electrode and tuned to the frequency of said high frequency oscillatory energy, a tuned circuit associated with the anode of said electron discharge device, the apparatus hav ing such adegree of feed-back that harmonics of said fundamental frequency will be present in the energy impressed upon said control electrode, one of said harmonics differing from said high frequency oscillatory energy by the frequency to which said tuned circuit associated with the anode is resonant, whereby the rectifying action by which the said harmonic and the high frequency oscillatory energy are caused to produce energy of a low frequency is performed by the same discharge device which produces the harmonic.

2. Apparatus for receiving and amplifying a high frequency oscillatory energy and producing energy corresponding thereto and of lower frequency, comprising an electron discharge device having a cathode, an anode and a control electrode, a tuned circuit associated with said control electrode and determining the fundamental frequency of said electron discharge device as an oscillator, a second circuit also associated with said control electrode and tuned to the frequency of said high frequency oscillatory energy, a tuned circuit associated with the anode of said electron discharge device, the apparatus 7 having such a degree of feed back that harmonies of said fundamental frequency will be present in the energy impressed upon said control electrode, one of said harmonics differing from said high frequency oscillatory energy by a super-audible frequenc the said circuit associated with thev anode being tuned 'to said super-audible frequency, whereby the rectifying action by which the said harmonic and the high frequency. oscillatory energy are caused to produce energy of a low frequency is performed by the same discharge device which produces the harmonic.

3. lhe method of heterodyning a signal by means of a single three-electrode tube which comprises generating by said tube a fundamental and harmonics thereof, one of said harmonics difi'ering from the frequency of said signal by a predetermined frequency, impressing the signal on the control electrode of said tube, combining by the rectifying action of said tube the signal and said harmonic to produce therefrom a beat frequency equal to said predetermined frequency and selecting said beat frequency from the frequencies present in the output of said tube.

,4. The method of heterodyning a signal by means of a single three-electrode tube which comprises generating by said tube a fundamental and harmonics thereof, one of said quency and selecting and'amplifying said I i beat frequency from the frequencies present in the output of said tube.

. In testimony whereof I aflix my signature.

HARRY W. HOUCK. 

